| 摘要 |
PURPOSE: To prevent deformation at the time of molding and to easily obtain an optical reflection surface having a desired concave surface shape by forming the rear side back surface of the optical reflection surface having the concave surface shape of desired curvature to the concave surface shape. CONSTITUTION: The concave surface mirror used for, for example, a laser writing device of a laser printer is integrally formed by injection and compression molding of an amorphous polyolefin and metal, such as aluminum or copper, is deposited by evaporation in its optical reflection surface 1. The mirror has a rectangular shape obtd. by forming the optical reflection surface 1 and the back surface 2 on the rear side thereof to the concave surface shape and is formed to the concave surface shape having the specified radius of curvature in a transverse direction by curving the plane in the transverse direction. The mirror is preferably formed to such curvature which satisfies|d1 -dz2|<1/w when the depth of the optical reflection surface is defined as d1 , the depth of the back surface as d2 and the width of either the optical reflection surface or the back surface, whichever wider, as W. As a result, the deformation directions on the optical reflection surface side and the back surface side are balanced backward against each other at the time when the central part is cooled.
|
